HES 350 Test 3

Heart, blood vessels, and red blood cells

What are the three main parts of the cardiovascular system

Systemic circulation

Blood flow from the heart out toward the body

Pulmonary circulation

Transports blood to the lungs

Heart - arteries - capillaries - veins - heart

What is the order that the blood flows through the body

Atria

• Upper chamber

• Thinner wall

• Receives blood from the venous circulation

Ventricles

• Lower chamber

• Thick muscular wall

• Receives flow from the atrium

• Main pump

Right side

What side of the heart provides bloods to the lungs

Left side

what side of the heart is supplying blood to the rest of the body

Valves

Chambers are separated by

Made up of these four

• Tricuspid

• Pulmonary semilunar

• Mitral

  • Aortic Semilunar

Blood vessels

• Superior and inferior vena cava fill the right atrium

• Pulmonary trunk splits into the pulmonary arteries

• Pulmonary veins bring blood to the left atrium

• Blood leaves the left ventricle via the aorta

Veins

• Have a lot less elastic properties in comparison to other blood vessels

  • Low pressure flow after the capillaries. Low pressure means valves are required to prevent backflow

Arteries

Role is to deliver high pressure flow from the heart to the tissue

Capillaries

Main role is estrange

has there different forms:

• continuous - very tight (brain)

• fenestrated - allows larger volumes to move across aveioliar level (kidneys)

• Sinusoid - very leaky (found in liver)

Cardiac myocyte

• Unlike the skeletal muscle cells which require a motor neuron, the cardiac myocytes form a network that can conduct electricity.

• Intercalated discs make it possible to have electrical conductivity

• Majority of cells in the heart are myocytes, however there is a larger system of conduction

Intercalated discs:

• Desmosomes - connect myocytes structurally

• Gap Junctions - connect myocytes electrically

SA Node

Autorhythmic cells - self depolarizing

• normal rhythm (pacemaker)

• Highest rate of inherent depolarization (sinus rhythm)

• Impulses spreads from SA node through atria by internode paths - atrial contractile cells and AV node

AV node

In atrioventricular septum

Connective tissue in septum prevents impulses spreading to ventricles without passing through AV node

Atrial cardiomyocytes

Pause in depolarization at AV node allows ….. to complete contraction before blood flows into ventricles

Atrioventricular bundle

(bundle of His)

• Proceeds through inter ventricular septum before dividing into 2 atrioventricular bundle branches (L/R)

Purkinkie fibers

spread impulse to ventricle contractile cells - need notes

Conduction system of the heart

1. The SA node and the remainder of the conduction system are at rest

2. The SA node initiates the action potential, which sweeps across the atria

3. After reaching the AV node, there is a delay approximately NOTES

membrane potential and ion movements - diagram and NOTES

Calcium

• Influx through the channels accounts for prolonged plateau phase and long absolute refractory

• Combine with troponin in tropomyosin complex

• 20% of it its required for contraction supplied by influx of it during plateau phase

  • Remaining amount is released from SR

Echocardiogram

Method for measuring electrical activity in the heart by the placement of electrodes on the skin

P wave

atria depolarization

• Patrica contraction 25 sec after start of P wave

  • Atria depolarization masked by QRS complex

QRS Complex

Depolarization of ventricles

• larger due to muscle size

  • ventricles contract as QRS reaches R wave peak

T wave

Repolarization of ventricles

Segments

Regions between 2 waves

intervals include segment and wave

Cardiac contraction

Contraction of atria to ventricular relaxation

Diastole

Relaxation; filling

Systole

Contraction; ejection

Atrial Systole

• Superior/inferior vena cava + coronary sinus - R atrium

• Pulmonary veins = left atrium

• AV (tricuspid and mitral) valves open - blood flows into ventricles

• 80% ventricular filling during diastole; 20% with atrial contraction

Ventricular systole

End diastolic volume (preload) = 130 mL

Phase 1 Increased pressure - tricuspid and mitral valves close; not enough pressure top open semilunar valves = isovolumic contraction

Phase 2 (ventricular ejection phase) - increased pressure opens semilunar valves - push blood into pulmonary trunk and aorta

End systomic NOTES

Ventricular Diastole

Phase 1 (isovolumic ventricular relaxation phase): Pressure in ventricle decreases below pulmonary trunk and aorta - semilunar valves close

Phase 2 (ventricular diastole): Pressure in ventricle drops below atria - tricuspid/mitral valves open - blood flows atria to ventricles

MAP

Mean arterial pressure

Average pressure in a person’s arteries across a cardiac cycle

= CO x TPR

= (Hr x SV) x TPR

Cardiac output

CO

A measurement of the amount of blood pumped by each ventricle in one minute (L/min)

Average resting CO is 4-8 L/min

Affects heart ate and the stroke volume

Total peripheral resistance

TPR

Heart Rate

HR

Regulated by both are of the autonomic nervous system

• cardioaccelerator and cardio inhibitory center in medulla oblongata

Stroke volume

SV

• slightly more complicated

• preload, contractility, and after load

higher pressure to lower pressure

Blood flow from

Perfusion

The movement of blood through a tissue

• In tissues, it ensures adequate delivery of oxygen and nutrient to support cell metabolism

• Arteries are medium size

• Capillaries are the smallest

  • Veins are the largest

Factors affecting heart rate

• autonomic innervation

• hormones

• fitness levels

  • age

Factors affecting stroke volume

• Heart size

• fitness levels

• gender

• contractility

• duration of contraction

• preload (EDV)

• afterload

SV = EDV - ESV

Preload

How full is the heart prior to contraction

• similar to end diastolic volume.

• As it increases, we have increased stretch on the heart

• The greater the stretch the more powerful the contraction is , which in turn increases SV and contractility

Contractility

The force of the contraction of the heart muscle. This is the main determinant of ESV and therefore, impact SV

Positive inotropic effect

Factors that increase contracility

Negative inotropic effect

Factors that decrease contractility

Afterload

To the tension that the ventricles mist develop to pump blood effectively against the resistance in the vascular system

Total Peripheral Resistance

The resistance of the vasculature to blood flow. Determined by a few key vascular features

• compliance

• blood volume

• blood viscosity

• blood vessel length

  • blood vessel diameter

Compliance

The ability of any compartment to expand to accommodate increased content

Blood volume

hypovolemia, hypervolemia

Blood viscosity

The thickness of fluids that affects their ability to flow

Blood vessel length

does not typically change in adults, but increases as we grow

Blood vessel diameter

can be altered by vasoconstriction (narrowing) or vasodilation (widening)

Blood flow

Poiseuille’s law

• viscosity doesn’t really change, length doesn’t really change

• The radius of a blood vessel is the major determinant of blood flow

Skeletal muscle Venous Pump

For blood to flow from the veins to the atria, the pressure in veins must exceed the atria

• pressure in the atria during diastole is incredibly low, often almost zero

• Physiological pumps increase venous pressure supporting venous return

• muscles relaxed valves closed

• muscles contracted valve above muscle opens

Cellular Respiration

Energy production in the cell

Respiration

Process of gas exchange at the lungs

carbon dioxide

Drives respiration because it monitors this gas

oxygen

oxygen and carbon dioxide

• Gases are small molecules that follow the same rules of diffusion

• both have a concentration gradient, they are not exchanged with one another

COnductiong Zone

Not involved in gas exchange

• all about getting air flow down into the respiratory zone

• typically larger structures

Nasal and oral cavity, nostril, pharynx, larynx, trachea, born his, lungs, and diaphragm

The structures in conduction zone

Right lung

Has three lobes

The bronchi is much more vertical

Respiratory zone

Gas exchange

Pleural membrane

Serous membrane surrounding lungs (visceral and parietal pleura)

• produce fluid to lubricate surfaces and reduce friction between layers

• Maintain position of lungs against thoracic wall

• pleurisy

• Pleural effusion

Visceral pleura

Sit against the organ

Parietal pleura

Sits against the chest wall

Pleurisy

Inflammation of pleura

• becomes rough, causing friction and pain

  • excessive fluid produced that relieves pain - exerts pressure on lungs; hinders breathing

Pleural effusion

Fluid acclimates in pleural cavity

Trachea

notes

Nasal cavity, trachea, bronchi

conductive zone

Epithelial Type: Pseudostratified, ciliated columnar epithelium, goblet cells

Key Features: Cilia beat mucus upward toward pharynx

Function: Traps and removes debris and pathogens

Larger bronchioles

Conductive zone

Epithelial Type: Simple ciliated columnar or cuboidal epithelium

Key Features: Fewer goblet cells; some club cells appear

Function: continue air cleaning; secrete surfactant - like fluid

Terminal bronchioles

Conductive zone

Epithelial Type: Simple cuboidal epithelium with club cells, no goblet cells

Key Features: Smooth muscle present; no alveoli

Function: Control airflow, protect airway lining

Respiratory bronchioles

Respiratory zone

Epithelial Type: Simple cuboidal epithelium, transitions to simple squamous

Key Features: Some club cells; few alveoli budding off walls

Function: Beginning of gas exchange

Alveolar ducts and alveoli

Respiratory zone

Epithelial Type: Simple squamous epithelium

Key Features: Two main cell types

Type 1: Pneumocytes: abundant, thin, flattened for diffusion

Type 2 pneumocytes: Cuboidal, secrete surfactant

Function: Gas exchange across thin barrier; surfactant reduces surface tension

Red blood cells

Important for both oxygen and carbon dioxide for transport

• plasma is majority of it includes water, proteins, electrolytes, a dissolved gases

• also made up of erythrocytes

Pulmonary ventilation

Act of breathing or the movement of air in and out of the lungs like blood flow, air also flows down a pressure gradient

Inhalation

Air must flow in

Exhalation

Air flows back out

Pressure difference

Lungs alter their volume from inhalation and exhalation, creating … which helps encourage flow

Boyles Law

The pressure of a gas is inversely proportional to its volume; If volume increases, pressure decreases

• P1V1=P2V2

compliance

Capacity for stretch to facilitate airflow

Airway Resistance

Resistance to flow

Compliance and airway resistance

Two things that affect the air moving through the body.

Atmospheric Pressure

Patm

• Force exerted by the atmosphere 1 atm or 760 mmHG

Intra-alveolar pressure

Palv

• changes across the breathing cycle

Intra-pleural pressure

Pip

Also changes across the breath cycle however, is always negative

negative pressure helps with suction

Elastic

What are lungs are made up of

• Recoil away from the thoracic cavity. Surface tension in alveoli also plays a role in this recoil

inspiration and expiration

Pulmonary ventilation has two major phases

• A complete respiratory cycle

  • quiet breathing vs forced breathing

Inspiration

• active

• Diaphragm and intercostal muscles contract

• Increases the volume of the thoracic cavity which decreases intra-alveolar pressure

• This creates a pressure gradient and air flows in

  • Pressure is decreasing

Forced Breathing notes

Accessory muscles (scalenes, sternocleidomastoid) and normally respiratory muscles contract more forcefully.

Expiration

• passive

• Lungs are elastic and this causes the lungs to recoil as the diaphragm and external intercostal muscles relax

• This muscle relaxation and elastic recoil increases intra-alveolar pressure above atmospheric pressure

• This creates a pressure gradient and air flow out

• Forced breathing

Forced breathing

Abdominal muscles (obliques) recrutiez to push the diaphragm up further. Internal intercostal muscles contract to pull ribs down further decreasing thoracic volume

Tidal volume

Air that normally enters and exits during quiet breathing

Expiratory/inspiratory reserve

The volume beyond tidal volume that can be expired and inspired during forced breathing

Residual volume

Air left in the lungs upon maximal exhale

Total lung capacity

Sum of all lung volumes or volume a person can hold in their lungs after forceful inhalaition

Vital capacity

Volume a person can move in or out of their lungs (TV +IRV+ERV)

Inspiratory capacity

Maximum amount of air that can be inhaled (TV+IRV)